Phase selector



Sept- K. c;. RIPLEY 2,254,243

PHASE SELECTOR Filed June 1'7, 1939 2 Sheets-Shet 1 T v I I \IVW l2 II OUTPUT voumes t 5 INPUT 1 VOLTAGE HEATER ,SCREEN VOLTAGE -1 PLATE VOLTAGE t VOLTAGE or VOLTAGE DIVIDER FIG. 2

ms'rm'rmsous msrmmusous PLATE PLATE CURRENT CURRENT AVERAGE CURRENT AVERAGE PLATE cggasu O l CYCLE 2 C CLES I WITH OUT-OF-PHASE INPUT TO GRID wma INPHASE mm to saw G- INVENTOR KENNETH c. RIFLE! FIG. 3

ATTORNEY I PLATE CURRENT Sept. 2, 1941.

INSTANTANEOUS 2 Sheets-Sheet 2 DIRECT CURRENT DIRECT CURRENT OUTPUT DUE TO INSTANTANEOUS DUE To PLATE CURREN ALTERNATING PLATE CURRENT ALTERNATING- CURRENT INPUT CURRENT IN- TO GRID PUT TO emu o ICYOLE 2 cvcuz' IcYcu-r z cYcLs? FIG. 5 FIG. 6

CAPACITANCE v v I SHUNT OUTPUT VOLTAGE INPUT g VOLTAGE g 5 E g 2 z I: Ill 2' :2 i 8 SCREEN 4 ems VOLTAGE 0F VOLTAGE own-31x,

FIG. 7

INVENTOR KENNETH c. RIPLEY Patented Se t. 2, 1941 UNITED STATES PATENT OFFICE PHASE ssmcflroa Kenneth c. Ripley, Washington, 1 0. Application June 17, 1939, Serial him-279,654

(Granted underthc act of March a, 1883, as amended April so, 1928; 310 o. G. 751) lclalm.

-Method of and apparatus for examining ferromagnetic articles was filed January 11, 1939.-

It is unnecessary to discuss the details of the operation of thatinvention except insofar as they affect the operation of the present invention.

In the drawings:

Fig. l ,is a diagrammatic view of a portion the device of the above-mentioned application Serial No. 250,383, with which the device of the present invention may be used;

Fig. 2 is a diagrammatic view of a pentode vacuum tube connected to function as an'ordinary amplifier; Figs. 3 and 4 are graphs showing the relation.

of the amplified phase and out-of-phase com-.

ponents of the grid voltageto the plate current of the tube of Fig. 2;

Figs. 5 and 6 are graphs showing the relations of the amplified portions of the two components of grid voltage when the amplifying device is arranged in accordance with the present invention; and

Fig. 'I shows a pentode tube amplifier circuit arranged in accordance with this invention.

In Fig. 1 the reference numeral I indicates an exciting coil, part of Canfields invention, through which passes an alternating current. Coils 2 carried by a magnetic yoke 3, are also a part of Canfields invention, and these coils in theoperation of his device have an alternating voltage induced therein.' This latter voltage contains components in phase and in quadrature with the current in thecoil I. In the application of Canfields invention it is useful to be able to separate and, estimate the magnitude of that component of voltage in coils 2 which is, in-phase (or 180 degrees out-of -phase) with the current in coil I.

The procedure hereto be described for separating' quadrature components of voltage makes use of an ordinary screen-grid vacuum tube, preferably a pentode vacuum tube, such as used in radio receivers.

If a pentode tube be connected to function as an ordinary amplifier, the two-quadrature components of the grid voltage are amplified alike.

If one component of .voltage is amplified one hundred times then the other component will likewise be amplifiedone hundred times'f0r the range of voltage where amplification is linear. The connections which are necessary for causing a pentode vacuum tube to operate as an ordinary amplifier are shown in Fig. 2.' The conductors 4 of 1 would be connected to conductors 5' of Fig. 2.

In Fig. 3 is shown the appearance of the .voltage wave'of that component of the plate. current of the tube of Fig. 2 which i in-phase with the current in coil I.

In Fig. 4 is shown the-appearance of the voltage wave of that component of the plate current which is in quadrature with the current in coil I.

In order to cause a tube of the type shown'in Fig. 2 to selectively amplify only that component of voltage in which one is interested, the operation of the tube must be made discontinuous.

,For instance, if the screen voltage of the radio tube werereduced to and held'at zero duringeach half cycle when the in-phase component of voltage was negative, the appearance of the amtion of the in-phase voltage would be an ordinary wave form with th negative portion thereof lopped oil, as shown in 5. The wave form for amplification of the quadrature component of the voltage would be an ordinary waveform with half of the positive portion and half of the negative portion lopped oil, as shown in Fig. ,6.

' alternating current voltage of proper value and in phase with the voltage of coil I, in practice it is more convenient to secure the desired intermittentblocking of the tube by the application of an alternating current voltage in phase with the voltage of coil I, superimposed on a certain divider 8. This point is so selected that any reduction in the voltage derived therefrom will cause blocking of the tube. 1

Coupled to the same line 6 by means of transformer I is a source of alternating current voltsating wave tom of age mm with the voltage in coil i. Such a source is conveniently secured by I ohmic resistance II, as shown in Fig. l, in series with coil I and connecting the conductors l2 leading irom the or this resistance to thelineslloil igfl.- g

with this arrangement of circuit connections component of the voltage in coil 2 may be observed to the exclusion oi the'quadrature componentby connecting a di- 7 rect-current voltmeter across'the coupling retorted somewhat, but not to any disadvantage. coupling resistor. I of Fig. I

with the alternating current The output 01 the will still be responding to, and only to, changes in that component oi'voltage which is in phase voltage applied to the screen-or the vacuum tube.

while the ioregoing description has been conflned to but one form oi execution of the insister 8 of Fig. 'l. The alternating character oi the amplified out-oi-phase component as shown. in Fig. 6 will prevent its registry on the voltmeter,

while the pulsating character the in-phase component will allow it to register.

For certainapplications it is desirable to smooth out the wave forms of Fig. 5. This may be done by the use' oi a low resistance shunt .designed to pass alternating current but not direct current. Therequiredshunt is a properly chosen capacitancelocated'as shown at II in Fig. 7. The shunt serves to transform the pulvoltage as shown in Fig. to direct-current voltage and to by-pass the alternatingwave form oi voltage shown in Fig. 6. The output'of the coupling reslstoroi' Fig. 7 will then be direct-current voltage which responds to, and only to, changes in the in-phase component oi the alternating-current in-put voltage;

The changingvalue of screen voltage during operating periods or the radio tube, due to the alternating component of. screen voltage, means that the wave forms of Figs. 5 and 6 will b disislimitedlo e v rthescopeandlimitationsoi thesubioinedclaim. v

The invention described herein may be manufactured and/or ,used by or for the Government of the United States of America for governmental purposes without the payment or royalticsthereonorthereior.

Iclaim:

Means ior selectively rectifying and ampliiy one of two quadrature components oranvoltsge, comprising a theralternating current mionic amplifying meanslhaving a control grid and a screen which when negatively biased past a certain point to be blocked, means impressing said alternating current voltage across said control grid, means impressing a direct current voltage on said screen value will and or such value that a reduction in said cause blocking of said ampliiying means,

means superimposing on said direct current voltage an alternating current voltag in-phase with that one or said two quadrature components which it is desired toampliiy.

bennderstoodthattheinvention will cause said amplifying means 

